1. Field of the Invention
This invention relates to the field of telecommunications and more specifically to a method and apparatus for providing Layer Two Tunneling Protocol (L2TP) forward error correction.
2. Description of Related Art
Layer Two Tunneling Protocol (L2TP) is a mechanism that enables automatic tunneling between a dialup user and a private network. L2TP may also be used to establish a Virtual Private Network (VPN) between two distinct IP networks connected by a third public network, such as the Internet. Unlike IP-in-IP tunneling, L2TP offers a number of advantages. For example, L2TP can encapsulate an entire PPP session within an X/IP/UDP session, where X is a data-link protocol. L2TP also allows for negotiation of session parameters via a virtual control channel and provides sequence numbers and retransmission mechanisms for reliability, flow control, and congestion control. L2TP is also extensible via user-defined extension headers.
A current L2TP protocol is discussed and detailed in the document entitled xe2x80x9cLayer Two Tunneling Protocol xe2x80x9cL2TPxe2x80x9dxe2x80x9d, Network Working Group, Request for Comments: 2661, August 1999 which is herein entirely incorporated by reference and to which the reader is directed to for further information.
Although there are advantages to using L2TP for tunneling between a remote user and a private network, L2TP has certain drawbacks. For example, L2TP does not allow for the use of error correction. For example, the current L2TP protocol does not allow for an established tunnel to include forward error correction. The protocol, therefore, does not allow either the remote user and/or the local network to enable forward error correction for an established tunnel. In addition, in instances where forward error correction is not required for the entire tunnel, the L2TP protocol does not allow for an established call or a plurality of calls within a tunnel to utilize forward error correction. Moreover, the L2TP protocol does not allow a routing device of a first private network, such as an Local Area Concentrator (LAC) router or Remote Access Concentrator (RAC), to establish forward error correction within an entire tunnel or just for a specific xe2x80x9csessionxe2x80x9d or call. There is, therefore, a need for forward error correction where L2TP is used.
The present invention relates to a method of establishing an L2TP tunnel between a first IP network and a first private IP network. A routing device of the first IP network is coupled to a public network and a routing device of the first private IP network is coupled to the public network. An L2TP tunnel is initiated from either the routing device of the first IP network or the routing device of the private IP network. An IP address from an address space of the first private IP network is provided and the L2TP tunnel is maintained between the routing device of the first IP network and the routing device of the second private IP network. Data traffic is tunneled between the first and the second IP network over the public network via the L2TP tunnel. A control mechanism is utilized for providing L2TP tunnel traffic error correction.
In another aspect of the invention, an L2TP call is established between a first IP network and a first private IP network. A routing device of the first IP network and a routing device of the first private IP network is coupled to the public network. An L2TP call is initiated between the routing device of the first IP network and the routing device of the private IP network. The first IP network is provided with an IP address of the first private IP network. The L2TP call is maintained between the routing device of the first IP network and the routing device of the second private IP network. The L2TP call traffic is tunneled between the first and the second IP network over the public network. A control mechanism is utilized for providing L2TP call traffic error correction.